I. Field of the Invention
This invention relates generally to portable metal finishing machines, and more particularly to split ring clamshell lathes of the type used to refurbish pipes, casings, engine shafts and the like in the field.
II. Discussion of the Prior Art
Split ring clamshell lathes of the type described herein are known in the art. U.S. Pat. Nos. 5,549,024, 4,739,685 and 4,939,964 to D. L. Ricci are illustrative of the technology involved. The split frame clamshell lathe generally comprises first and second semi-circular segments that are designed to be joined together so as to surround the pipe or shaft to be machined. The resulting annular assembly includes a stationary ring portion that becomes clamped to the workpiece and an abutting rotatable portion, including a ring gear, that is journaled to the stationary portion for rotation about the concentrically disposed workpiece. An air-operated, hydraulically-operated or an electrically-operated motor is operative coupled to the assembly and includes a drive gear designed to mesh with the ring gear on the rotatable segment of the clamshell lathe. Also mounted on the rotatable segment of the clamshell lathe is a tool block for supporting a cutting tool that can be made to advance in the radial direction against the pipe to be machined in incremental steps upon each revolution of the ring gear.
In these prior art arrangements, the drive motor mounts to the outside diameter of the stationary annulus and projects parallel to the longitudinal axis of the workpiece clamped within the central opening of the clamshell lathe. It frequently happens that in the field the pipe or shaft to be machined is in close proximity to neighboring structures which frequently make it difficult to place the clamshell lathe about the pipe or shaft to be turned. The motor, which typically projects approximately 18-20 inches either rearward or forward of the ring assembly, is a common source of difficulty in the desired placement of the clamshell lathe. Thus, a need exists for a motor mount fixture that will afford greater flexibility in the placement of a clamshell lathe.
The present invention affords a solution to the foregoing problem. In particular, it provides a motor mount that allows the motor to be selectively disposed at a plurality of different angular dispositions in a plane parallel to the plane of the clamshell lathe ring structures. As such, the motor position can be adjusted to avoid any nearby structures that might otherwise interfere with a desired placement of the clamshell lathe relative to the workpiece to be machined. This ease of set-up is especially important when working in environments where exposure to nuclear radiation must be kept to a minimum.
The foregoing objects, features and benefits of the invention are achieved by providing a motor mount for a clamshell lathe that comprises a drive gear housing that is adapted to be clamped or otherwise fixedly attached to the non-rotatable ring member of the clamshell lathe along with a gear box that is attachable to the drive gear housing at any one of a plurality of selectable angular positions. A first shaft is journaled for rotation in the drive gear housing and the gear box. This first shaft carries the pinion gear that mates with the clamshell""s ring gear periphery, and a bevel gear is arranged to mesh with an input bevel gear that is journaled for rotation within the gear box. The input bevel gear, in turn, is adapted to be driven by one of an air motor, an electric motor or a hydraulic motor.
To provide a desired angular disposition of the drive motor relative to the clamshell lathe assembly, there is attached to the drive gear housing an annular bracket that is provided with a plurality of regularly, circumferentially-spaced threaded apertures extending through its thickness dimension for receiving the threaded ends of at least one bolt passing through and aperture(s) in the gear box housing.